1. Field of the Invention
The present invention relates to a clamping jig for clamping semiconductor laser bars formed by cleaving a semiconductor wafer into a number of bars, and particularly to a clamping jig used for forming a reflection coating of predetermined reflectivity by vapor deposition or sputtering on a predetermined face of each semiconductor laser bar.
2. Description of the Related Art
In many cases, a semiconductor laser device has a configuration wherein reflection coating is formed with predetermined reflectivity on the optical beam output end face of a laser chip.
Formation of the aforementioned reflection coating is made as follows. First, a number of electrodes 101 are formed on a semiconductor wafer 100, following which cleavages 102 are formed between adjacent electrodes 101, as shown in FIG. 7A.
Subsequently, as shown in FIG. 7B, the semiconductor wafer 100 is cleaved into a number of bars so as to form multiple laser bars 100a (which are each formed in the shape of a bar having multiple electrodes linearly arrayed thereon).
Conventionally, each divided laser bar 100a is mounted on a clamping jig, following which the clamping jig mounting the laser bar 100a is mounted on a holder in a vapor deposition chamber. The holder for mounting the clamping jig is provided at the upper portion in the chamber and a vapor source is provided at the lower portion in the chamber.
Vapor deposition is performed as follows. First, the chamber is evacuated to a predetermined degree of vacuum. Subsequently, the vapor deposition material loaded into the vapor source is heated by an electron beam or the like so as to evaporate, thereby forming reflection coating on a side face of the laser bar 100a (such side face corresponds to an end face of a laser chip). Thus, by the aforementioned vapor deposition, the reflection coating made of a vapor deposited film is formed on a side face of the laser bar 100a. 
However, with the above-described conventional vapor deposition method, the work for mounting laser bars has been troublesome since each laser bar 100a is mounted on a single clamping jig. In particular, in the case where vapor deposited films are to be formed on the faces of both sides of a laser bar, when a vapor deposition process for one side of the laser bar is finished, the laser bar must be removed and reset so as to expose the other side face of the laser bar, which is a troublesome work.
A means has been proposed as disclosed in Japanese Unexamined Patent Application Publication No. 2002-164609, wherein multiple laser bars are mounted on a single clamping jig so as to perform vapor deposition onto both end faces while keeping the laser bars mounted on the clamping jig.
With the vapor deposition process disclosed in Japanese Unexamined Patent Application Publication No. 2002-164609, the multiple laser bars 100a are mounted on a clamping jig A shown in FIG. 8 so as to be piled with the face, on which the electrodes 101 have been formed, facing the piling direction. The clamping jig A is formed in the shape of a “U” having three closed sides and one open side. A groove B is formed in each of the two closed sides in a manner such that the grooves B face one another so as to allow the laser bars 100a to be piled at the bottom portion of the clamping jig A with both longitudinal ends of the laser bars fitted into the grooves. The multiple laser bars 100a are piled up on the bottom face of the clamping jig A.
Thus, the laser bars 100a are mounted on the clamping jig A in a manner such that both sides of the laser bars are exposed, except for both longitudinal ends thereof. The clamping jig A mounting the multiple laser bars 100a are mounted in the chamber of the vapor deposition apparatus, following which vapor deposition is performed.
With the vapor deposition apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2002-164609, the multiple laser bars 100a are mounted on the clamping jig A and their vapor deposition can be performed at the same time. Furthermore, with the aforementioned clamping jig A, the laser bars 100a are mounted with both side faces being exposed, and accordingly, vapor deposition can be performed for both side faces simply by adjusting the direction in which the clamping jig faces the vapor source.
However, the multiple laser bars 100a mounted on the clamping jig A are subjected to vapor deposition process with both end portions thereof fit within the grooves B of the clamping jig A. Accordingly, both ends of the laser bar 100a are not coated with vapor deposited films, i.e., no reflection coating is formed on either ends, creating a problem in which both ends are useless for forming any semiconductor laser product.
Furthermore, the two grooves B are formed with a fixed depth thereof and a fixed length therebetween, creating a problem that the laser bar 100a formed with a length out of a predetermined range cannot be mounted onto the clamping jig A. Accordingly, a particular clamping jig A for vapor deposition needs to be made corresponding to the length of the laser bars 100, which is impractical for general application. Furthermore, a laser bar 100a which has been broken into a short length in the cleaving process cannot be mounted on such a clamping jig A.
If any of the laser bars 100a is broken and falls down from the clamping jig A after being mounted thereon, a gap is created in a pile of the laser bars 100a, which results in a problem that any of the laser bar 100a may incline, causing irregularity in the film thickness of the reflection coating on the side face of each laser bar.
With the clamping jig A, the laser bars 100a are mounted so as to fit the grooves B. Accordingly, in the event that a portion near the end of the laser bar 100 is damaged due to contact with the corner of the groove B, the damaged portion is useless for forming any semiconductor laser product.
The aforementioned clamping jig A is formed in the shape of a “U” having a single open side and three closed sides as shown in FIG. 8, creating a problem in which the clamping jig A is readily deformed due to heat. Deformation of the clamping jig A creates a problem of deformation of the laser bars mounted thereon.